Swifties have it on good authority that the pop star is about to make an appearance in an upcoming landmark episode of the never-ending medical drama.

Is Taylor Swift about to make a guest appearance in 'Grey's Anatomy'? It's looking highly likely.

Fans of the 'All Too Well' pop star have been scouring the internet for signs that the new Doctor of Fine Arts will be doing just that - and they've stumbled upon a recent IMDb listing for the 'Grey's Anatomy' 400th episode (yes, really), which points to all of their wildest dreams coming true.

"The Swift Society" on Twitter shared the casting list for the upcoming release, which will be part of the series' 18th season. Is Doctor Swift about to make a musical number happen on the show? With 18 seasons and 400 episodes down, we guess anything could happen.

The potential Taylor Swift 'Grey's Anatomy' appearance may have been scuppered, with the guest star no longer listed in the cast line-up on the movie database website. Weirdly enough though, Miss Piggy, yes that Miss Piggy, is also listed as a guest star. Dare we dream of a duet between the two?

However, there is a discrepancy we'd like to point out - the episode titled 'Out for Blood' (which further fuels the pop star's appearance due to her 'Bad Blood' bop) is actually listed as the series' 399th episode, while the 400th episode is titled 'You are the Blood'. But hey, they've both got "blood" in the title, right? And it's a double-episode finale, so let's just go with it. Having said that, let's take all of these rumours with a huge dose of salt.

T-Swizzle previously said that she was a fan of the long-running medical drama, saying that Ellen Pompeo's character Meredith Grey was her favourite. The 'Grey's' actor recently told Extra TV that Swift is "pretty busy" for a cameo, but should it ever happen, it would be "fun" and something she'd "love" to see.

The double-episode finale will air in the US on Thursday, May 26. Sky Witness and NOW are currently airing season 18 in Ireland and the UK.